1. Field of the Invention
This invention relates to an improved method of transporting viscous hydrocarbons, such as crude oil, from a well or between two points via pipeline.
In particular, the present invention relates to an improved method for increasing the pumpability and transportability of viscous hydrocarbons containing at least 10-15% water by adding thereto an effective amount of a solution or dispersion of a surfactant in a nonaqueous solvent therefor.
2. Description of Prior Art
The transportation of low gravity crudes throughout the entire production system from bore hole to the surface and then via pipeline to refinery is very difficult due to their high viscosity and resultant low mobility.
Three methods are currently used for increasing the pumpability and the transportability of viscous hydrocarbons, such as heavy crudes.
One method utilized to assist the flow of viscous hydrocarbons in pipelines is the installation of heating equipment downhole and/or at frequent intervals along the pipeline, whereby the crude is heated to reduce its viscosity and thereby facilitate its transport. Heaters employed for this purpose can be operated by withdrawing some of the crude being transported for use as fuel. This procedure, however, is costly to install and maintain and may result in the loss of as much as 15 to 20% of the crude being transported.
Another method used to reduce the viscosity of heavy crudes and increase their pumpability and transportability is the introduction of a low viscosity hydrocarbon diluent, e.g., light oil, kerosene distillates or the like into the well bore or pipeline to dilute or thin the viscous hydrocarbon crude.
Both of the above methods have become quite expensive as the cost of energy and dilution stocks has risen dramatically.
A third method for increasing the pumpability and transportability of viscous hydrocarbons is the addition thereto of an aqueous solution of a surfactant which forms a low viscosity oil-in-water emulsion. This method has proved effective in a number of instances. For example, U.S. Pat. No. 3,380,531 and U.S. Pat. No. 3,467,195 teach the improvement of viscosity by the addition of an aqueous solution of a nonionic surfactant. Similarly, prior patents disclose the use of high salt content emulsion (U.S. Pat. Nos. 3,487,844, 3,943,954, 4,099,537 and 4,108,193), the use of low water cuts (U.S. Pat. Nos. 3,425,429 and 3,519,006) and blends of surfactants (U.S. Pat. Nos. 4,239,052, 4,246,919, 4,249,554 and 4,265,264).